ceph/src/boost/libs/hana/example/functional/fix.cpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #include <boost/hana/assert.hpp>
   6 #include <boost/hana/config.hpp>
   7 #include <boost/hana/functional/fix.hpp>
   8 namespace hana = boost::hana;
   9
  10
  11 BOOST_HANA_CONSTEXPR_STATELESS_LAMBDA auto factorial = hana::fix([](auto fact, auto n) -> int {
  12     if (n == 0) return 1;
  13     else        return n * fact(n - 1);
  14 });
  15
  16 int main() {
  17     BOOST_HANA_CONSTEXPR_CHECK(factorial(5) == 120);
  18 }